The present invention relates in general to apparatus for detecting the presence of an intruder, and more particularly to apparatus that detects the presence of an intruder, identifies the location in which the intrusion is detected and discriminates against noise interference to reduce false alarms.
In the patent to William F. Kyle, Jr., U.S. Pat. No. 3,774,190, issued on Nov. 20, 1973, for Intrusion Alarm With Signal Processing And Channel Identification, there is disclosed intrusion detection apparatus. The intrusion detection apparatus comprises a plurality of groups of sensors. Each group of sensors is located in a discrete area. Sensors are activated to detect the presence of an intruder and to identify the zone of the intrusion.
Intrusion Detection Systems, Inc. of San Leandro, Calif., manufactures a seismic system SSP-1 to SSP-12 in which detector sensors are activated to transmit seismic signals to a signal processor for the operation of an alarm. Discriminator sensors are employed to screen or cancel unwanted noises to reduce false alarms. The detector sensors are operated off one bus and the discriminator sensors are operated off another bus.